gitea/web_src/js/markup/codecopy.ts

import {svg} from '../svg.ts';

export function makeCodeCopyButton(): HTMLButtonElement {
  const button = document.createElement('button');
  button.classList.add('code-copy', 'ui', 'button');
  button.innerHTML = svg('octicon-copy');
  return button;
}

export function initMarkupCodeCopy(elMarkup: HTMLElement): void {
  const el = elMarkup.querySelector('.code-block code'); // .markup .code-block code
  if (!el || !el.textContent) return;

  const btn = makeCodeCopyButton();
  // remove final trailing newline introduced during HTML rendering
  btn.setAttribute('data-clipboard-text', el.textContent.replace(/\r?\n$/, ''));
  el.after(btn);
}